With global warming becoming an increasingly serious issue worldwide, the development of environmentally friendly refrigeration and air-conditioning systems has become increasingly important. Refrigerants have a great influence not only on global warming, but also on the performance of refrigeration and air-conditioning systems. Therefore, the selection of a refrigerant has an important role in reducing carbon dioxide emissions that contribute to global warming.
Recently, various partially-fluorinated propenes having a double bond in the molecule, with a lower global warming potential (GWP) than known chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), and hydrofluorocarbons (HFCs), have been proposed.
2,3,3,3-Tetrafluoropropene (HFO1234yf) is one such propene (see, for example, Patent Literatures 1 and 2). This refrigerant is flammable, and ignites at a concentration of 6.5 to 12.5 vol. % in air at 21° C.